--On 28 January 2008 16:26:57 +0000 Mike Cardwell <[EMAIL PROTECTED]> wrote:
> Ian Eiloart wrote: > >>> The "headers_remove = User-Agent" line is something entirely different >>> that tends to help. You'll find many references on the web to hotmail >>> blocking certain messages that contain Thunderbird in the User-Agent >>> header, but allowing through messages that are exactly the same, but >>> without the User-Agent header. I tested this myself a while back and it >>> was true. >> >> Why would an MUA add a "User-Agent" header? It's an HTTP or net-news >> header, not a mail header. >> <http://www.iana.org/assignments/message-headers/perm-headers.html> >> Arguably, Microsoft are doing the right thing by punishing clients for >> using non-standard headers. > > Non-standard headers? You can add *any* arbitrarily named header you > want to an email. At least Thunderbird and Mutt both use "User-Agent". > I've not tested other MUAs. Microsoft aren't, "doing the right thing," > or anything even close to sensible by scoring so harshly on this header. RFC2822 does say that you can add other headers, but not arbitrarily named - the name can't clash with a registered name. However, that doesn't mean that every imaginable header is "Standard". Indeed rfc2076 lists several headers as "not internet standard". I'd suggest that a "standard" header is one that's registered with IANA according to rfc3864: <http://tools.ietf.org/html/rfc3864>. I guess, for clarity, I should have used the phrase "registered". I suspect that Microsoft are adding spam points to messages with non-standard headers, which would explain why some messages are acceptable when they don't contain a user-agent header. >> Perhaps the sensible thing to do is to replace the User-Agent header >> with an X-mailer: header >> >> Or, perhaps someone should register user-agent as a mail header. >> <http://tools.ietf.org/html/rfc3864> says how, and says that part of the >> point is "encouraging convergence of header field name usage across >> multiple applications and protocols" > > Or perhaps Microsoft should drop SmartScreen and use a decent filtering > technology. > > Mike -- Ian Eiloart IT Services, University of Sussex x3148 -- ## List details at http://lists.exim.org/mailman/listinfo/exim-users ## Exim details at http://www.exim.org/ ## Please use the Wiki with this list - http://wiki.exim.org/
